In manufacturing semiconductor devices, processings such as, for example, a film forming processing, an oxidation processing, a diffusion processing, an annealing processing, and an etching processing, are performed on a substrate which is a workpiece (e.g., a semiconductor wafer (hereinafter, referred to as a “wafer”)). In general, these processings are performed in a vertical substrate processing apparatus including a heater device, which is able to process a plurality of wafers in a batch type.
The substrate processing apparatus generally includes a sealed storage container (e.g., FOUP) that stores wafers to be conveyed to the substrate processing apparatus from a previous step, a wafer boat that stores the wafers during a processing, and a loading area where wafer transfer is performed between the storage container and the wafer boat. A process tube (processing container) and a heater device are provided in an upper space of the loading area. The wafer boat that stores the wafers is disposed in the process tube through an elevating mechanism.
In general, below the wafer boat, a cover is formed integrally with the wafer boat to cap a manifold provided on an opening side of the process tube in order to maintain the airtightness in the heater device during the substrate processing. When the manifold is capped by the cover, it is required that the cover elastically abuts on the manifold. Further, after being abutted, the cover needs to be closely adhered to the manifold with a predetermined degree of adhesion (see, e.g., Japanese Patent Laid-Open Publication No. H05-21421).